Along with rapid development of the Internet and popularization of large-screen multifunctional mobile phones, a great deal of mobile data multimedia services and various high-bandwidth multimedia services emerge, such as the mobile data multimedia services of video conferencing, television broadcasting, video on demand, advertising, online education, interactive games and the like. Increasing service requirements of mobile users are met on one hand, and on the other hand, new service increasing points are also brought to mobile operating companies. These mobile data multimedia services require multiple users to simultaneously receive the same data, and compared with ordinary data services, have the characteristics of large data volume, long duration, time delay sensitivity and the like.
In order to effectively utilize mobile network resources, the 3rd Generation Partnership Project (3GPP) raises a Multimedia Broadcast Multicast Service (MBMS), and such a service is a technology of transmitting data from a data source to multiple targets, thereby implementing sharing of a network (including a core network and an access network) resource and increasing a utilization rate of the network resource (particularly an air interface resource). The MBMS defined by the 3GPP may not only implement pure-text and low-rate message multicast and broadcast but also implement high-speed multimedia service broadcast and multicast to provide various video, audio and multimedia services, which undoubtedly follows a tendency of future mobile data development and provides a broader service prospect for development of a 3rd-Generation (3G) mobile communication technology.
In Long Term Evolution (LTE), an MBMS may adopt a multicast mode, called a Multicast Broadcast over Single Frequency Network (MBSFN) sending mode, the MBMS service adopting the multicast mode may also be called an MBSFN service, and multiple cells may adopt the same modulation and coding scheme and send the same content by adopting the same physical resource. Multi-cell transmission of the MBMS has the following characteristics:
1) the MBMS is synchronously transmitted in an MBSFN area;
2) multi-cell MBMS transmission combination is supported;
3) a Multicast Traffic Channel (MTCH) and a Multicast Control Channel (MCCH) are mapped to a Multicast Channel (MCH) in a Point-to-Multipoint (p-T-m) mode; and
4) an MBSFN synchronization area, the MBSFN area, MBSFN transmission, advertisement and a preservation cell are all semi-statically configured by operation and maintenance. In such a manner, User Equipment (UE) of multiple cells may receive multiple pieces of MBMS data with the same content and perform SFN combination, thereby increasing a gain of a received signal. Multiple cells which send the same MBMS by adopting the same physical resource and an MBSFN sending mode form an MBSFN area.
During practical LTE networking, a plurality of MBSFN services exist in an MBSFN area, and all of these MBSFN services belonging to the same MBSFN area form an MBSFN service group. In other words, an MBSFN service group belongs to only one MBSFN area. An MBSFN area may include multiple cells, and an MBSFN service group which is completely the same is for each cell. Data channels MTCHs with multiple MBSFN services of the same MBSFN area and a control channel MCCH of the MBSFN services may be multiplexed to an MCH. An MCCH and multiple MTCHs of the same MBSFN area, i.e. multiple logical channels, may be mapped to the same transmission channel MCH; and the MCH is born through a Transport Block (TB) of an MBSFN sub-frame.
In a related technology, an MCH Sub-frame Allocation Pattern (MSAP) occasion is simultaneously introduced into the concept of MSAP, and it indicates all multicast resources included in an MCH corresponding a certain MSAP within a time period of a dynamic scheduling period. In an MSAP occasion, multiple MTCHs and dynamic scheduling information may be sent, and an MCCH may also be included. The dynamic scheduling information is born in a Media Access Control (MAC) Protocol Data Unit (PDU) Control Element (CE). A time length of an MSAP occasion is a scheduling period, and may also be called an MCH Scheduling Period (MSP), the MSP maximally being 10,240 ms. An MCH may allocate one or more MBSFN sub-frames in one or more MBSFN frames through an MSAP, wherein a sub-frame sent in a multicast mode is called an MBSFN sub-frame, and a frame including an MBSFN sub-frame is called an MBSFN frame. An MCH may include multiple MTCHs, that is, the multiple MTCHs are multiplexed to the same MCH.
On each MSAP occasion configured by an MCH, dynamic scheduling information is born, mapping information from MTCHs to auxiliary MSAP sub-frames is contained, and the mapping information is determined by virtue of an MBSFN sub-frame number index relationship in a scheduling period. UE may read the scheduling information to know allocation of each MTCH on the MBSFN sub-frames, and the UE may read an interested MTCH on the corresponding MBSFN sub-frame and neglect the MBSFN sub-frames not required to be read, so that MBMS receiving efficiency of the UE is improved, and power consumption of the UE is reduced. MBSFN sub-frame numbers mentioned here are determined as follows: all MBSFN sub-frames allocated by an MCH within a scheduling period are sequentially arranged and sequentially numbered.
In an existing LTE technology, multiple logical channels multiplex an MCH in a manner as follows: a sub-frame corresponds to a Transmission Time Interval (TTI), a TB may be sent in a TTI and each data TB corresponds to a MAC PDU. A MAC PDU may include multiple MAC Service Data Units (SDUs), and these MAC SDUs may be from different logical channels, the logical channels probably including an MTCH, an MCCH and the like. Data from different logical channels is sent together on a physical channel after being connected in series in the MAC PDUs.
In an LTE enhanced MBMS (eMBMS), a Common Sub-frame allocation Period (CSP) is adopted to allocate MCHs of MBSFN sub-frames in an MBSFN area in the MBSFN area, that is, the same CSP is adopted for multiple MCHs in an MBSFN and the same sub-frame allocation mode is adopted in each CSP. FIG. 1 is a schematic diagram of an MSP and a CSP according to the related technology. As shown in FIG. 1, MCH1, MCH2 and MCH3 exist in an MBSFN area; and MBSFN sub-frame resources are allocated to each MCH in a CSP, wherein the same sub-frame allocation mode is adopted in the CSP. An MSP may include multiple CSPs, and under a normal condition, a minimum MSP value is adopted for the CSPs. The MSP is for each MCH, that is, each MCH may have different MSPs, but multiple MCHs in an MBSFN area have the same CSP, a maximum value of the CSP is 2,560 ms and a maximum value of the MSP is 10,240 ms.
FIG. 2 is a schematic diagram of a dynamic MBMS MCH Scheduling Information (MSI) MAC CE according to the related technology. As shown in FIG. 2, a MAC PDU sub-header containing a Logical Channel Identifier (LCID) is adopted for identification. The MAC CE has a variable length, which is 2x bytes (x is a number of elements in an MBMS-SessionInfoList sequence). Each MTCH should include the following fields:
(1) LCID: this field is configured to indicate an LCID of the MTCH, and a length of the field is 5 bits; and
(2) Stop MTCH: this field is configured to indicate a sequence number of a stop sub-frame of the corresponding MTCH in an MSAP occasion, a length of the field is 11 bits, a specific Stop MTCH value 2047 indicating that the corresponding MTCH is not scheduled and values in a range from 2043 to 2046 are reserved.
If a certain MTCH in an MAC PDU is not sent, 2047 may be adopted to identify this stop MTCH.
However, in the related technology, UE may not correctly receive a required MBMS under the condition that required sub-frame resources allocated to a certain MBMS in an MCH exceeds 2,043 sub-frames, and for this, there is yet no corresponding solution.